Which of the following statements is not true?
a. you are exposed to nuclear radiation every day.
b. most of the nuclear radiation to which it is exposed occurs naturally in the
environment.
c. natural nuclear radiation is called background radiation.
d. all natural radiation is at a level low enough to be safe.

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s. part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.

Determine the largest intensity w of the uniform loading that can be applied to the frame without causing either the average normal stress or the average shear stress at section b–b to exceed σ=19 mpa and τ=24 mpa, respectively.

As you lift an 88 n box straight upward you produce a power of 72 w. what is the speed of the box?